Antimicrobial Resistance Monitoring in Salmonella and E. coli

To provide continuity of monitoring data and allow epidemiological tracing of isolates with particular patterns of resistance (particularly in relation to certain Salmonella serovars), it is recommended that those antimicrobials listed in previous recommendations should remain in future testing requirements. The rationale for inclusion of the antimicrobials recommended for use in current monitoring programmes has been previously described elsewhere (EFSA, 2007, 2008, 2012a), in particular regarding the phenotypic monitoring of the presumptive ESBL‐producing and AmpC β‐lactamase‐producing bacteria in animals and food, and the inclusion of last‐resort antimicrobials in the treatment of certain infections with highly resistant Gram‐negative bacteria in humans, such as the carbapenems and colistin. It is reinforced that isolates are tested for susceptibility and MICs interpreted using the epidemiological cut‐off values and concentration ranges shown in Table 9 to determine the susceptibility of Salmonella spp., and indicator commensal E. coli.
All E. coli isolates deriving from the specific monitoring of ESBL‐/AmpC‐/carbapenemase producing E. coli, as well as those randomly selected isolates of Salmonella spp. and E. coli deriving from the routine monitoring that, after testing with the first panel of antimicrobials are found to be resistant to cefotaxime, ceftazidime or meropenem, should be further tested with a second panel of antimicrobial substances as shown in Table 10. This panel notably includes cefoxitin, cefepime and clavulanate in combination with cefotaxime and ceftazidime for the detection of presumptive ESBL and AmpC producers, as well as imipenem, meropenem and ertapenem to phenotypically identify presumptive carbapenemase producers.